SI Units:-
density - 1kg per meter cubed
==conservation of energy states: energy is neither created or destroyed but changes from one form to another==
our main energy source is the SUN
forms of energy
potential energy
potential energy has 3 different types (elastic, gravitational,chemical). It is @@stored energy@@ and it @@has to be released@@
chemical potential energy: energy stored i fuels, food and batteries.
^^kinetic energy^^
all moving things contain kinetic energy
the heavier an object is, the more kinetic energy it has.
^^heat energy^^
heat energy is split into three parts (conduction, convection and radiation)
conduction- is when two metal surfaces are in contact with each other. The heat is not then transferred by this contact.
convection- the flow of heat caused by the motion of a liquid or a gas.
radiation- energy that moves from one place to another (this is how the heat from the sun travels to the earth since radiation does not require particles)
to keep out heat and keep in the warmth are made from thatch bricks and cement
^^electrical energy^^
the national grid is a network of power lines that carry high voltages of electrical energy to towns, cities, etc
a car uses e/e for providing a spark in the battery to ignite the fuel and getting the fuels moving
sources of electrical energy include:- power stations(thermal,hydro,nuclear) and batteries (potential chemical).
alternate e/e sources:
windmills-kinetic energy of the wind
nuclear-heat energy from splitting atoms
generators-chemical energy in petrol/diesel
solar energy - contains both heat and light energy. panels trap light energy and create electrical energy using photo-voltaic cells. the energy is now stored in batteries and used to power appliances.
^^light energy^^
sources-
light enables you to see things
does not require particles in order to move
light travels in straight lines
plants use light energy during photosynthesis to produce simple sugars(chemical potential energy)
photosynthesis = carbon dioxide + water + sunlight
^^sound energy^^
any object that vibrates produces sound
a vibration is a small but very fast backwards and forwards motion.
sound does not travel through a vacuum because it requires particles. this is why we don’t hear things exploding in space
sound travels faster in water than in air because water particles are more closer together than air particles (so there would be more vibrations of particles)
sound moves by the vibrations in the air causing your ear drums vibrate and these vibrations are interpreted by the brain.
wind instruments(flutes, trumpets,etc)-cause the column of air to vibrate
stringed instruments- strings are made to vibrate
percussions- you need to release kinetic energy onto the drum to make it vibrate.
The Human Voice
the larynx (voice box) is made up of thin membranes stretched across a space.
these membranes are called vocal chords
how does a thermal power station work?
potential—heat—kinetic—electrical energy
how does a hydro-electrical power station?
biomass- energy from plants